1. Field of the Invention
The present invention relates generally to optical switching, and particularly to monitoring the performance of optical switches.
2. Technical Background
Over the past several decades, fiber optic technology has transformed the telecommunications industry. A decade ago, network designs included relatively low-speed transceiver electronics at each end of a communications link. Light signals were switched by being converted into electrical signals. The electrical signals were switched using electronic switches, and converted back again into light signals. The bandwidth of electronic switching equipment is in the Gigahertz range. On the other hand, the bandwidth of single mode fiber is in the Terahertz range. As the demand for bandwidth increased, network designers have sought ways to exploit the bandwidth in the 1550 nm region. Optically transparent switching fabrics were developed to meet this demand.
In one approach that is being considered, optical designers are evaluating free-space plane-to-plane optical interconnects, often referred to as three-dimensional optical cross-connects (3D OXCs). 3D OXCs have the potential to make large scale Nxc3x97N switching a reality. For example plane-to-plane interconnects can be designed to easily scale to high port counts on the order of 4000 by 4000 ports. MEMS mirror arrays and conventional collimator arrays can be easily scaled to keep pace with port count growth.
One drawback to this approach relates to the fact that traditional monitoring capability does not scale as favorably. MEMS mirror arrays and collimator arrays can be fabricated using batch processing techniques. However, monitoring components required at each port have to be added later. Per port monitoring is provided by splicing in a light source, light detector, and other associated optical elements at each port in the switch fabric. Thus, the manufacturing process becomes increasingly complicated and costly. Since monitoring components have to be spliced into each port, the amount of fiber that must be managed by the switch is also increased. Both the splicing operations and the increase in the amount of fiber result in reduced switch reliability.
What is needed is an integrated monitoring approach that eliminates the aforementioned problems. A scalable monitoring approach that employs batch processing techniques is needed to reduce costs, simplify the manufacturing process, reduce the amount of fiber employed in the switch, and increase switch reliability.
The present invention addresses the needs described above. The present invention provides a scalable monitoring approach that reduces costs, simplifies the manufacturing process, reduces the amount of fiber employed in the switch, and increases switch reliability.
One aspect of the present invention is a collimator assembly that includes a first microlens array and a second microlens array. The first microlens array includes at least one first microlens element. The second microlens array includes at least one second microlens element. A monitor transceiver array is disposed between the first microlens array and the second microlens array, the monitor transceiver array including at least one monitor transceiver element coupled to the at least one first microlens element and to the at least one second microlens element.
In another aspect, the present invention includes a method of making a collimator assembly. The method includes providing a first microlens array, the first microlens array including at least one first microlens element. A second microlens array is provided, the second microlens array including at least one second microlens element. A monitor transceiver array is disposed between the first microlens array and the second microlens array. The monitor transceiver array includes at least one monitor transceiver element. The at least one monitor transceiver element is coupled to the at least one first microlens element and to the at least one second microlens element.
In another aspect, the present invention includes a three-dimensional optical switch. The optical switch includes a first collimator array that includes a first monitor transceiver array disposed between a first pigtailed microlens array and a first free-space microlens array. The first pigtailed microlens array has at least one first pigtailed array element. The first monitor transceiver array includes at least one first monitor transceiver element optically coupled to the at least one first pigtailed array element. The first free-space microlens array includes at least one first free-space microlens element optically coupled to the at least one first monitor transceiver element. A beam steering apparatus is coupled to the first collimator array. A second collimator array is coupled to the beam steering apparatus. The second collimator array includes a second monitor transceiver array disposed between a second pigtailed microlens array and a second free-space microlens array. The second pigtailed microlens array has at least one second pigtailed array element. The second monitor transceiver array includes at least one second monitor transceiver element optically coupled to the at least one second pigtailed array element. The second free-space microlens array includes at least one second free-space microlens element optically coupled to the at least one second monitor transceiver element.
In another aspect, the present invention includes a method for monitoring the performance of an optical switch. The optical switch includes a first collimator array having at least one first port array element, and a second collimator array element having at least one second port array element. The method includes directing the at least one light signal into the optical switch via the at least one first port array element. At least one transmission path monitoring signal is superimposed onto the at least one light signal to thereby form at least one superimposed signal. The at least one transmission path monitoring signal is generated by the at least one first port array element. The superimposed signal is directed to the at least one second port array element. The at least one transmission path monitoring signal is received by the at least one second port array element, and the at least one light signal being directed out of the optical switch via the at least one second port array element.
Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the description serve to explain the principles and operation of the invention.